1. Field of the Invention
The subject invention relates generally to a warning system for a charge hopper, and, more particularly, to a warning system for use on mobile-type concrete mixers to signal the operators thereof when the concrete mixers' charge hoppers are in a raised position.
2. Background of the Related Art
Mobile-type concrete mixers are the workhorse in the building industry. There are tens-of-thousands of such concrete mixers in operation today throughout the world. Their basic function is to mix and deliver tons of concrete to a variety of settings including residential and industrial construction sites. Mobile-type concrete mixers can be classified into two groups--tractor-carried concrete mixers and tractor-drawn concrete mixers.
The tractor-carried concrete mixers have two basic configurations. They include a conventional configuration which is loaded and delivers concrete from the rear of the vehicle and a front-loader configuration which, as the name implies, is loaded and delivers concrete from the front of the vehicle. Although configured differently, they share similar characteristics. That is, they each include a cab for the operator to drive the vehicle, an air supply system, a mixing drum, frames to support the mixing drum, a charge hopper, and controls for operating the mixing drum and charge hopper.
Tractor-drawn concrete mixers basically comprise a trailer-mounted concrete mixer that is pulled by a tractor. They tend to have a larger capacity then tractor-carried concrete mixers and are often used for large pours such as found in highway and dam construction. Although configured somewhat differently then the tractor-carried concrete mixers, tractor-drawn concrete mixers share similar characteristics. That is, they include a cab in the tractor for the operator to drive the vehicle, an air supply system, a mixing drum, frames to support the mixing drum, a charge hopper, and controls for operating the mixing drum and charge hopper.
Both tractor-carried concrete mixers and tractor-drawn concrete mixers may alternatively be referred to simply as concrete mixers. To simplify the description of the present invention, reference will be made only to tractor-carried cement mixers. Those skilled in the art will appreciate that the present invention will benefit any and all types of mobile-type concrete mixers.
Referring to FIGS. 1 and 2, a perspective view of a conventional tractor-carried concrete mixer designated by reference numeral 10 and an elevational view of a rear portion of the concrete mixer 10 are illustrated, respectively. In the descriptions provided herein below, like reference numerals identify similar structural elements.
As noted above, a tractor-carried concrete mixer 10 includes a cab 12 that provides a protective enclosure in which the operator drives the truck and controls various functions of the concrete mixer. Concrete mixer 10 also includes an air supply system that provides compressed air for actuating a breaking system, for actuating pneumatic cylinders, and for general-purpose usage. The air supply system includes a compressor that is driven by the tractor's engine and charges a volume tank 14 to store compressed air for the above-described purposes.
Concrete mixer 10 further includes a mixing drum 16 for mixing and storing cement, aggregate, and water, i.e., concrete. The mixing drum 16 has a closed end and an open end. The open end is an access port 18 through which cement, aggregate, and water are poured into the interior of the mixing drum 16 and out of which concrete is poured.
The controls 19 are typically located within eyeshot of the access port 18 to enable an operator to manipulate the controls 19 while observing delivery of concrete from the mixing drum 16. The type and number of controls 19 vary from concrete mixer to concrete mixer. However, all concrete mixers include a control to operate the mixing drum 16, and to raise and lower the charge hopper as described in more detail herein below.
The mixing drum 16 is rotationally supported by a set of frames including a cab-side frame 20 and a hopper-side frame 22. The cab-side frame 20 supports the closed end of the mixing drum 16 through a tapered roller bearing (not shown). The hopper-side frame 22 supports the open end of the mixing drum 16 through a pair of rollers (not shown) that ride against a support ring 24 attached to the mixing drum 16. Extending from the upper portion of the hopper-side frame 22 is a near-side vertical support 26 and a complementary far-side vertical support (not shown).
The charge hopper 28 is funnel-shaped and is utilized in a lowered position to guide cement, aggregate, and water from storage containers at a concrete plant, through the access port 18, and into the mixing drum 16. The charge hopper 28, when moved to a raised position, allows concrete to pour unobstructed from the mixing drum 16, out through the access port 18, down a chute attachment 30 (shown in its stored position), and into, for example a pour frame.
The near-side vertical support 26 and far-side vertical support provide mounting points for the charge hopper 28. More specifically, the charge hopper 28 is pivotally mounted by a near-side pivot pin 32 to a near-side attachment arm 34 which is attached to the near-side vertical support 26, and a complementary far-side pivot pin to a far-side attachment arm (not shown) which is attached to the far-side vertical support.
A first end 38 of a pneumatic lift cylinder 36 is mounted to the near-side vertical support 26 and a second end 40 is mounted to the charge hopper 28 for pivoting the charge hopper 28 between the lowered position and the raised position. That is, the charge hopper 28 is pivoted from the lowered position to the raised position by extending the pneumatic lift cylinder 36, thereby pivoting the charge hopper 28 in the counter-clockwise direction about the pivot pins as indicated by the "Y" arrow (FIGS. 1 and 3). The charge hopper 28 is pivoted from the raised position to the lowered position by retracting the pneumatic lift cylinder 36, thereby pivoting the charge hopper 28 in the clockwise direction about the pivot pins as indicated by the "X" arrow (FIGS. 1 and 2). The charge hopper 28, illustrated in FIGS. 1 and 3. is shown in the raised position while the charge hopper 28 illustrated in FIG. 2 is shown in the lowered position. Although the lift cylinder 36 is described herein as a "pneumatic" lift cylinder, such lift cylinders might also be hydraulically operated.
Those skilled in the art will appreciate that when the charge hopper 28 is in the raised position it increases the overall height of the tractor-carried concrete mixer 10 by approximately one to two feet. Therefore, proper operation of the concrete mixer 10 dictates that the charge hopper 28 should be located in the lowered position any time the vehicle is traveling over roadways; thereby preventing it from accidentally hitting low overpasses, power cables, light poles, etc., and causing severe property damage and personal injury. However, due to a wide variety of distractions found at construction sites, it is relatively easy for an operator to forget that the charge hopper is in the raised position.
It would be beneficial to provide a system to warn an operator of a tractor-carried concrete mixer or tractor-drawn concrete mixer that the charge hopper is in the raised position. Such a system should be relatively inexpensive, easy to install, operate and maintain.